Electrical precipitation



April 12, 1949; H. A. WINTERMUTE 2,467,068

ELECTRICAL PRECIP I'I'ATION Filed Aug. 30, 1945 electrical sign as the discharge electrode.

Patented Apr. 12 1949 ELECTRICAL PRECIPITATION Harry A.- Wintermute, Plainfield, N. J., assignor to Research Corporation, New York, N. Y., a corporation of New York Application August 30, 1945, SerialNo. 613,55

In the operation of electrical precipitators, gases 7' containing solid or liquidparticles in suspension are passed through an electric field in which the particles become electrically charged by attraction of electrons or ions and are then attracted to an electrically charged member upon which the charged particles are collected. In the twostage or separated field type of precipitator, the suspended particles in the gas are charged by passing the gas between two opposed electrodes between which a high potential difference is maintained, one of the two electrodes being a discharge electrode at which there is silent or corona discharge that ionizes the gas and causes the suspended particles to become charged with the same This is the first or chargin stage. In the second or collecting stage, the gas containing all or a substantial proportion of the charged particles passes into a second or precipitating electrical field, typically maintained between opposed non-discharge electrodes, wherein the charged particles migrate under the influence of the electric field to one of the electrodes between which the field is maintained and are deposited thereon. The electrode upon which the material is deposited is termed a collecting electrode and the opposed electrode, whether it is a discharge or a non-discharge electrode may conveniently be designated as a precipitating electrode.

An object of the invention is to provide a simple and efiective apparatus for the energization of the electrodes of two-stage precipitators.

A further object of the invention is the provision of apparatus for energizing the collecting stage of a two-stage precipitator from the same source as the energization of the chargin stage but at lower peak voltages.

Another purpose of the invention is to provide a simple apparatus for energizing a plurality of associated two-stage precipitators.

Other objects and advantages of the invention will be apparent from the following description.

In general, the invention comprises apparatus for energizing two-stage electrical precipitators wherein the precipitatin electrode of the collecting stage is maintained at a relatively high potential with respect to the collecting electrode by the transfer of charges from the discharge electrode system of the charging stage to the precipitating electrode of the collecting stage through an air gap. The electrical precipitators of the invention are characterized by the fact that the precipitating electrode system of the collecting stage is insulated fromthe other electrode systems of the precipitator and is charged by the transfer of charges thereto from the discharge electrode system of the precipitator either solely through the stream of gas passing from the chargin to the collecting stage or through a discharge gap particularly provided for this purpose. The discharge electrode system of the precipitator may be charged by a substantially continuous or a pulsating unidirectional potential from a suitable source, or the discharge electrodes of parallel or successive sections of a precipitator may be energized by successive half waves of a source of high potential of alternating polarity or of pulsating unidirectional polarity.

The apparatus of the invention is particularly useful in the energization of air cleaning precipitators of the type described in my application Serial No. 576,734, filed February 8, 1945, now U. S. Patent 2,443,780, issued June 22, 1943 and will be more particularly described for the purpose of illustrating the principles of the invention in connection with such air cleaning precipitators with reference to the accompanying drawing in which The sole figure is a diagrammatic representation of a two-stage electrical precipitator and associated energizing means embodying the principles of the invention.

In the precipitator shown in the drawing, A is the charging stage and B is the collecting stage; II] are the discharge electrode members of the charging stage comprising a supporting rod Illa and a discharge wire Hlbj II are the non-discharge electrodes of the charging stage comprising extended surface members; It are the precipitating electrodes of the collecting stage; and

, l3 are the collecting electrodes of the collecting stage, electrodes l2 and 13 being typically extended surface electrodes, for example, rods or plates. The non-discharge electrodes ii of stage A and the collecting electrodes [3 of stage B are connected to the grounded terminal of a power pack [6 supplying substantially continuous unidirectional current at, for example, 15 11v. The discharge electrodes ll] of stage A are connected to the other terminal of the power pack and are thereby charged to approximately 15 kv. potential with respect to the non-discharge electrodes. The precipitating electrodes it of stage B are insulated from the other electrode systems of the precipitator and a charging device comprising, for example, a plate I! connected to the discharge electrode system of stage A and a set of corona points I8 connected to the precipitating electrodes of stage B, provides a controlled air gap charge leak whereby the latter electrodes may be maintained at any predetermined potential below the potential of the discharge electrode system, by suitably adjusting the spacing of plate I! and points [8. The spacing may be controlled automatically by electrostatic repulsion or by other known devices.

It will be seen that the apparatus of the invention makes possible simple and largely selfregulating energization of two-stage electrical precipitators. Arc-overs and other electrical diseliminated because the method of energizing this stage limits the maximum instantaneous current available to the charge capacity of the precipitating electrode system.

I claim:

An electrical precipitator including a charging stage comprising opposed discharge and nondischarge electrode systems and a collecting stage including opposed precipitating and nondischarge collecting electrode systems, said stages being arranged for flow of a stream of gas '15 turbances in the collecting stage are substantially to be cleaned successively through said charging stage and said collecting stage, means electrically connecting the non-discharge electrode system of the charging stage and the non-discharge collec'ting electrode system of the collecting stage to one terminal of a high potential current source, means electrically connecting the discharge electrode system ofthe charging stage to the other terminal of the high potential current source, and means including an air gap positioned externally of the gas stream flowing through said charging stage and said collecting stage for transferring charges from said other terminal to the precipitating electrode system of the collecting stage.

HARRY A. WINTERMUTE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,114,682 Gumaer Apr. 19, 1938 2,295,152 Bennett Sept. 8, 1942 2,326,237 Lissman Aug. 10, 1943 2,351,089 Abbey June 13, 1944 

